Diseases such as cancer or those caused by pathogen-infection are often treated with drugs (e.g., chemotherapeutics and antibiotics). In order to kill the cancer or diseased cells, the drug(s) must enter the cells and reach an effective dose so as to interfere with essential biochemical pathways. However, some cells evade being killed by the drug by developing resistance to it (termed “drug resistance”). Moreover, in some cases, cancer cells (also called tumor cells or neoplastic cells) and damaged cells (e.g., pathogen-infected cells), or the pathogens themselves, develop resistance to a broad spectrum of drugs, including drugs that were not originally used for treatment. This phenomenon is termed “multidrug resistance” (MDR). There are different types of MDR, each associated with a different biological mechanism, and there are specific biological “markers” for different types of MDR that are clinically useful for detecting and diagnosing each type of MDR.
MDR can involve cancer cells or infectious pathogens such as viruses, bacteria, parasites and other microorganisms that may be present in cells or body fluids. The emergence of the MDR phenotype is the major cause of failure in the treatment of infectious diseases (see Davies J., Science 264: 375-382, 1994; Poole, K., Cur. Opin. Microbiol. 4: 500-5008, 2001). Patient cross-resistance to different anti-microbial and anti-cancer agents, which are structurally and functionally distinct, can cause serious problems for pathogen-infected patients. Similarly, the development of multidrug resistant cancer cells is the principal reason for treatment failure in cancer patients (see Gottesman, M. M., Ann. Rev. Med. 53: 615-627, 2000).
Multidrug resistance is multifactorial. The classic MDR mechanism involves alterations in the gene for the highly evolutionarily conserved plasma membrane protein (P-glycoprotein or MDR 1) that actively transports or pumps drugs out of the cell or microorganism (Volm M. et al., Cancer 71: 3981-3987, 1993); Bradley and Ling, Cancer Metastasis Rev. 13: 223-233, 1994). Both human cancer cells and infectious bacterial pathogens may develop classic MDR via mechanisms involving the overexpression of P-glycoprotein due to amplification of the gene encoding P-glycoprotein. The overexpression of P-glycoprotein mRNA or protein in MDR cancer cells or pathogen-infected cells is a biological marker for MDR. Diagnostic tests and therapeutic methods have been developed that make use of the overexpression of P-glycoprotein marker to diagnose and to treat MDR cancer and pathogen infections (Szakacs G. et al., Pathol. Oncol. Res. 4: 251-257, 1998). However, because various normal tissues express different amounts of P-glycoprotein, there are significant problems with side effects as any therapy that targets P-glycoprotein on the cell surface of MDR cancer cells would also affect those normal tissues that also have a relatively high level of P-glycoprotein expression, such as liver, kidney, stem cells, and blood-brain barrier epithelium.
“Atypical MDR” is a term used to describe MDR cancer cells or pathogens wherein the mechanism of multidrug resistance is unknown, novel, or different from the classic mechanism involving P-glycoprotein. For example, human lung tumors are multidrug resistant but do not have alterations in P-glycoprotein (see Cole S. P. et al., Science 258: 1650-1654, 1992). Rather, they express another drug transporter (the multidrug resistance associated protein or “MRP1”). A new mechanism of MDR was recently described that involves lung resistance related protein, which is a marker for this type of atypical MDR (Rome L. H. et al., PCT Pub. No. WO9962547). Other examples of atypical markers for MDR include MRP5, which is a novel mammalian efflux pump for nucleoside analog drugs (see Fridland and Schuetz, PCT Pub. No. WO0058471) and certain sphingoglycolipids (see U.S. Pat. No. 6,090,565). It should be noted that MDR cells may express more than one MDR marker (both classical P-glycoprotein and atypical markers) simultaneously on the same cell, and that the markers are expressed independently (Grandjean F, et al. Anticancer Drugs, 12:247-258, 2001). It is therefore possible to combine treatments directed against more than one cell surface MDR marker and potentially against more than one mechanism of MDR.
Intermediate filaments are a major component of the cytoskeleton of higher eukaryotic cells. Intermediate filaments are composed of a number of different structurally related proteins and different intermediate filament protein genes are expressed in different tissues. Studies involving spontaneous and experimentally produced mutations in intermediate filament genes have demonstrated that intermediate filaments function to enhance the mechanical stability of epidermal and muscle cells (Evans R. M., BioEssays, 20: 79-86, 1998). Vimentin (gi/4507895) is a homodimeric intracellular protein found in class III intermediate filaments in mesenchymal and other nonepithelial cells and in the Z disk of skeletal and cardiac muscle cells. (See, e.g., Evans, R. M. (1998) Bioassays 20:79-86; Herrmann, H., Aebi, U. (2000) Curr. Opin. Cell Biol. 12:79-90, ibid. (1998) Subcell Biochem 31:319-62.). Vimentin is a phosphoprotein whose phosphorylation is enhanced during cell division. Both the human and murine vimentin genes have been characterized (see, e.g., Kryszke et al. (1998) Pathol. Biol. 46:3945; Paulin, D. (1989) Pathol. Biol. 37:277-82). Purified eukaryotic vimentin has a molecular mass of 54 kDa, is soluble in its native form and insoluble when denatured. Vimentin gene regulation appears to participate in several steps of viral infections (reviewed in Kryszke et al. (1998) Pathol. Biol. 46:39-45).
Various cytoskeleton modifications are associated with malignant cell transformation and have been used as prognostic factors. In contrast to the in vivo situation where vimentin expression is characteristic of cells of mesenchymal origin, vimentin synthesis is characteristic of all proliferating cells in vitro regardless of their embryonal origin, and is switched off upon differentiation of certain precursor cells. Vimentin gene expression is upregulated in some metastatic tumor cells, and is thus a marker for oncogenic progression (see, Kryszke et al. (1998) Pathol. Biol. 46:3945; Osborn et al. (1989) Curr. Comm. in Mol. Biol., Cold Spring Harbor Press).
Vimentin and other IF proteins have been used in the histological classification of human tumors (for reviews see Ramaekers et al. (1982) Cold Spring Harb. Symp. Quant. Biol. 46: 331-339; Thomas et al. (1999) Clin. Cancer Res. 5:2698-2703). Vimentin in particular has been used as a marker for de-differentiation in several types of tumors.
Tumor markers that co-localize with vimentin and other intermediate filaments have been described. For example, De Bernard, Marina (WO0127269) describes a novel marker for neuroblastomas called VIP54, a protein that is closely associated with vimentin and desmin filaments, and the use of this internal marker for the detection and cellular imaging of intermediate filaments (particularly class-III vimentin or desmin filaments) as a markers for tumor development and/or progression.
Finally, there are several examples that show changes in the expressed level and intracellular distribution of vimentin in different types of human solid tumors and solid tumor cell lines, often in association with the development of multidrug resistance (Conforti G, et al., Br. J. Cancer, 3:505-511, 1995; Moran E. et al., Eur J. Cancer, 33:652-660, 1997).
There remains a need in both humans and animals for detecting, treating, preventing, and/or reversing the development of both classical and atypical MDR phenotypes in cancer cells and non-cancerous damaged cells, regardless of how the MDR arises (e.g., naturally occurring or drug-induced). In addition, the ability to identify and to make use of reagents that identify multiple drug resistant cells has clinical potential for improvements in the treatment, monitoring, diagnosis, and medical imaging of multidrug resistant cancer and multidrug resistant damaged cells.